Production of hexahydropyrimidine aldehydes



United States Patent US. Cl. 260251 11 Claims ABSTRACT OF THE DISCLOSURECompounds of the formula wherein X is oxygen or sulfur, R through R arehydrogen or alkyl radicals, R and R are neopentanal radicals or one of Rand R can be alkyl are useful as textile treating agents. The compoundsare prepared by treating 4-hydroxy-2-pyrimidinone with formaldehyde andan aldehyde, e.g., isobutyraldehyde, in the presence of a strong acid.

The invention relates to the production of hexahydropyrimidinedialdehydes and trialdehydes by the reaction of4-hydroxyhexahydropyrimidines or 4-alkoxyhexahydropyrimidines withformaldehyde and an aldehyde or with an aldehyde alone, and to newsubstances of this It is the object of this invention to provide a newprocess for the production of hexahydropyrimidine dialdehydes andtrialdehydes bearing, as substituents, aldehydoalkyl groups in the4-position and in the 1- and/ or 3-position, an oxygen atom or sulfuratom in the 2-position and other substituents in the 5-position and ifdesired in the 6-position, in good yields and by a simple method.

Another object of the invention is to provide new hexahydropyrimidinedialdehydes and trialdehydes which bear, as substituents, aldehydoalkylgroups in the 4-position and in the 1- and/or 3-position, an oxygen atomor sulfur atom in the 2-position and other substituents in the5-position and if desired in the 6-position.

In accordance with this invention these and other obiects are achievedand hexahydropyrimidine aldehydes having the general formula:

X H R1N/ N-RZ a I R1 0 HC-CCHO I R4 (I) R8 R5 R (I) in which:

R denotes a hydrogen atom or an alkyl radical, R denotes a hydrogen atomor an alkyl radical, R denotes an alkyl radical,

R denotes an alkyl radical, R denotes an alkyl radical,

R denotes an alkyl radical, R and R denote the radical:

in which R and R have the above meanings, or one of the radicals R and Rdenotes an alkyl radical, and X denotes an oxygen atom or a sulfur atom,are obtained in a very simple way and in good yields (a) by reacting ahexahydropyrimidine having the general formula:

X II 110.4? III-R10 R ;C 30-01% R4 Rfl in which the radicals R R R and Rand X have the above meanings, R and R both denote hydrogen atoms or onedenotes a hydrogen atom and the other an alkyl radical, R denotes ahydrogen atom or an alkyl radical,

with formaldehyde and an aldehyde having the general formula.

in which the radicals R and R have the above meanings, in the presenceof an acid and in the presence or absence of a solvent and/or diluent attemperatures of from 0 to 120 C., preferably from 40 to C., using amolar ratio of starting material to formaldehyde to aldehyde having theFormula III of about 1:2:3 when reacting starting materials having theFormula II in which the redicals R and R both denote hydrogen atoms, andusing a molar ratio of starting material to formaldehyde to aldehydehaving the Formula III of about 1:1:2 when reacting starting materialshaving the Formula II in which one of the radicals R and R denotes analkyl radical and the other denotes a hydrogen atom, or (b) by reactinga hexahydropyrimidine derivative having the general formula:

in which the radicals R R R R and R and X have the meanings given aboveand R denotes a hydrogen atom or an alkyl radical, with an aldehydehaving the general formula:

in which the radicals R and R have the above meanings, in a molar ratioof 1:3 in the presence of an acid and in the presence or absence of asolvent and/ or diluent at a temperature of from 0 to C., preferably offrom 3 40 to 100 C., or (c) by reacting a hexahydropyrimidine having thegeneral formula:

II C R -C HC-OR" Ii 1'1 (v) in which R R R R R and X have the abovemeanings, one of the radicals R or R denotes a hydrogen atom and theother denotes the radical CH OR in which R has the above meaning, withformaldehyde and an aldehyde having the Formula HI in a molar ratio ofabout 1 1:3 in the presence of an acid and in the presence or absence ofa solvent and/or diluent at a temperature of from 0 to 120 C.,preferably from 40 to 100 C.

The process may be represented for example for the reaction of5,5-dimethyl-4-hydroxyhexahydropyrimidine with formaldehyde andisobutyraldehyde as follows:

In the formulae of the compounds which are preferred 7 as startingmaterials, the radicals R R R R R R and R or R denote hydrogen atoms oralkyl radicals having one to eight carbon atoms, and R R R and R denotealkyl radicals having one to seven carbon atoms. The followinghexahydropyrimidine derivatives may for example be used as startingmaterials: 4-hydroxy- 5,idimethyl-Z-oxohexahydropyrimidine, 4hydroxy-5,5- dimethyl-6-isopropyl 2 oxohexahydropyrimidine, 4hydroxy-S-ethyl-S-butyl-6-isoheptyl 2-oxohexahydropyrimidine and thecorresponding 4-hydroxy-2-thiohexahydropyrimidines. Examples of othersuitable starting materials are: 4methoxy-S,5-dimethyl-Z-oxohexahydropyrimidine, 4-methoxy-5,5-dimethyl 6isopropyl 2 oxohexahydropyrimidine,4-ethoxy-5,5-dimethyl-6-isopropyl-2-oxohexahydropyrimidine and thecorresponding 4-alkoxy-2-thiohexahydropyrimidines.

The formaldehyde may be used as an aqueous solution, as paraformaldehydeor in the form of trioxane or formaldehyde acetals.

Among the aldehydes having the Formula HI, isobutyraldehyde,Z-methylpentanal and 2-ethylhexanal are particularly suitable.

The simultaneous reaction of a 4-hydroxyhexahydropyrimidine derivativeor 4-alkoxyhexahydropyrimidine in which at least one of the radicals Rand R denotes a hydrogen atom, with formaldehyde and an aldehyde havingthe Formula III in the presence of an acid is the most simple procedureand at the same time the most economical embodiment of the processaccording to this invention. It is also possible however to use thecorresponding N-monomethyl, N-alkoxymethyl, N,N'-dimethylo1 orN,N'-dialkoxymethyl compounds of 4-hydroxyhexahydropyrimidine or4-alkoxyhexahydropyrimidin derivatives for reaction with the CH-acidaldehydes.

The corresponding monomethylol or dimethylol compounds may first beprepared from the 4-hydroxy-2-oxo- 4 hexahydropyrimidines, 4alkoxy-Z-oxohexahydropyrimidines, 4-hydroxy-2-thiohexahydropyrimidinesor 4-alkoxy- 2-thiohexahydropyrimidines with formaldehyde and thesereacted in a further reaction stage with an aldehyde having the FormulaIII in the presence of an acid. When an alkanol is present, thecorresponding alkoxymethyl compounds are formed which may also bereacted.

Examples of suitable methylol compounds are: N,N'- dimethylol-4-hydroxy5,5 dimethyl-2-oxohexahydropyrimidine, N,N-dimethylol-4-hydroxy 5,5dimethyl-6- isopropyl-2-oxohexahydropyrimidine, Nmethyl-N-methy1ol-4-hydroxy-5,5-dimethyl-2 oxohexahydropyrimidine,N-monomethylol-4-hydroxy 5,S-dimethyl-6-isopropyl-2-oxohexahydropyrimidine, N,N'-dimethylol-4-methoxy-5,5- dimethyl 2oxohexahydropyrimidine, N,N' dimethoxymethyl-4-methoxy-5,5-dimethyl 2oxohexahydropyrimidine and the corresponding methylol and alkoxymethylcompounds of 4-hydroxy-2-thiohexahydropyrimidines and4-alkoxy-2-thiohexahydropyrimidines.

The acids used should advantageously be acids which do not oxidize underthe reaction conditions, for example hydrogen chloride, sulfuric acid,oxalic acid, toluenesulfonic acid, benzenesulfonic acid or ionexchangers containing sulfonic acids. The acids are advantageously usedin amounts of 1 to 30% by weight with reference to the total amount ofstarting materials.

It is advantageous to carry out the reaction in the presence of solventsand/or diluents, such as Water, tetrahydrofuran or dioxane. The solventsand/or diluents may be used singly or mixed together.

In general the reaction of the substances takes place in the statedmolar ratios. Slight deviations from these molar ratios, for example ofup to 10 mole percent, are however possible.

The process according to this invention involves a condensation reactionwhich can be accelerated by adding more acid, with or without raisingthe reaction temperature. In many cases it is possible to obtain thedesired hexahydropyrimidine aldehydes at low temperatures in thepresence of larger amounts of acid. On the other hand it is alsopossible to carry out the reaction at higher temperatures in thepresence of less acid. The temperature chosen will depend on thereactants used and can be lowered by increasing the amount of acid addedand vice versa.

The compounds obtainable by the process are textile finishing agents andvaluable intermediates, for example for the production of textile andleather auxiliaries. Thus for example textile cloth may be impregnatedtherewith at the rate of 40 to 250 g. of said compounds per kg. offibrous material from an aqueous suspension, dried at 70 to 140 C. andthus finished; a stiff, smooth, polished, full or hard handle of thetextile cloth may be obtained depending on the constitution of thecompounds concerned.

The invention is further illustrated by the following examples in whichparts are by weight.

EXAMPLE 1 parts of 50% aqueous sulfuric acid is added to a mixture of144 parts of 2-oxo-4-hydroxy-5,S-dimethylhexahydropyrimidine, 200 partsof 30% aqueous formaldehyde solution and 216 parts of isobutyraldehydein a stirred apparatus having a reflux condenser and heated for fivehours at refluxing temperature while stirring. The refluxing temperaturerises from 60 C. to about C. in the course of the first three hours.After the reaction is over, the whole is cooled to room temperature andneutralized with dilute caustic soda solution. The reaction product isexhaustively extracted from the reaction mixture with chloroform. Thechloroform phase is driedwith sodium sulfate and the .chloroform isevaporated. =290 parts of a crude product is obtained whichis subjectedto fractional distillation in a high vacuum. The fraction which passesover at from 207 to 220 C. at 0.5 mm. Hg

is collected separately. 208 parts of2-oxo-5,5-dimethylhexahydropyrimidyl-l,3-dineopental-4-isobutyraldehydeis obtained.

Analysis.Calculated for C H Q N (366), percent: C, 65.6; H, 9.3; N,7.65. Found, percent: C, 65.4; H, 9.5; N, 7.4.

EXAMPLE 2 A mixture of 492 parts of 2-oxo-l,3-dimethoxymethyl-4-methoxy-5,S-dimethylhexahydropyrimidine, 432 parts of isobutyraldehydeand 100 parts of concentrated hydro- 1 chloric acid is heated for fivehours at refluxing temperature in a stirred apparatus having a refluxcondenser, the refluxing temperature rising from 70 C. to about 83 C. inthe course of three hours. The reaction mixture is neutralized withdilute caustic soda solution and extracted with chloroform. Thechloroform solution is dried with sodium sulfate and evaporated in awater-jet vacuum. 742 parts of crude product is obtained. It is purifiedby means of a high-vacuum fractional distillation. 376 parts of 2-.oxo-5,S-dimethylhexahydropyrimidyl 1,3 dineopental-4- in which:

R denotes a hydrogen atom or an alkyl radical having one to eight carbonatoms; R denotes a hydrogen atom or an alkyl radical having one to eightcarbon atoms; R denotes an alkyl radical having one to seven carbonatoms; R denotes an alkyl radical having one to seven carbon atoms; Rdenotes an alkyl radical having one to seven carbon atoms; R denotes analkyl radical having one to seven carbon atoms; R and R denote theradical:

R1 -0H--0H0 R i in which R and R have the above meanings, or one of theradicals R and R denotes an alkyl radical having one to eight carbonatoms and X denotes an oxygen atom or a sulfur atom.

2. 2 oxo5,5-dimethylhexahydropyrimidyl-1,3-dineopental-4-isobutyraldehyde. 3. Aprocess for the production of a hexahydropyrimidine aldehyde having thegeneral formula:

X H C in which:

.R is hydrogen or alkyl of 1 to 8 carbon atoms, R is hydrogen or alkylof 1 to 8 carbon atoms,

R is alkyl of 1 to 7 carbon atoms,

in which R R R R and X have the above meanings, R and R both denotehydrogen or one of them denotes hydrogen and the other alkyl of 1 to 8carbon atoms, R denotes hydrogen or alkyl of 1 to 8 carbon atoms, withformaldehyde and an aldehyde having the general formula:

1'1 (III) in which the radicals R and R have the above meanings, in thepresence of a strong acid which does not oxidize under reactionconditions, at a temperature of from 0 to C., the amount of acid beingfrom 1 to 30% by weight based on the total weight of the startingmaterials, using a molar ratio of starting material to formaldehyde toaldehyde having the Formula III of about 1:2:3 when reacting startingmaterials having the Formula II in which the radicals R and R bothdenote hydrogen atoms, and using a molar ratio of starting material toformaldehyde to aldehyde having the Formula III of about 1:1:2 whenreacting starting materials having the Formula II in which one of theradicals R and R denotes an alkyl radical and the other denotes ahydrogen atom.

4. A process for the production of a hexahydropyrimidine aldehyde havingthe general formula:

in which:

R is hydrogen or alkyl of 1 to 8 carbon atoms, R is hydrogen or alkyl ofl to 8 carbon atoms, R is alkyl of 1 to 7 carbon atoms, R is alkyl of 1to 7 carbon atoms, R is alkyl of 1 to 7 carbon atoms,

R is alkyl of 1 to 7 carbon atoms, R and R each denotes the radical:

1 -OHa-(E-CHO in which R" and R have 'the above meanings or one of theradicals R and R denotes alkyl of 1 to 8 carbon atoms, and X is oxygenor' sulfuncwhieh process comprises: v r

R OCHz N \NCH20R12 R HG-OR" R4 (ll-R I V A a (Iv) in which R R R R andvXhave the meanings given above and R and R denote hydrogen or alkyl of 1.to 8 carbon atoms, with an aldehyde having the general formula:

;.H-+- 0Ho R8 111 in which R and R have the above meanings, in amolarratio of 1:3, in the presence of a strong'acid which does not oxidizeunder reaction conditions and at a teinp eratureof from 0 to 120 C., theamount of acid being from 1 to 30% by weight based on the total Weightof the starting materials.

5. A process for the production of a hexahydropyrimidine aldehyde havingthe general formula:

in which: H a

R is hydrogen or alkyl of 1 to8 carbon atoms, R is hydrogen or alkyl of1 to 8 carbon atomS,, R is alkyl of 1 to 7 carbon atoms, R is alkyl of 1to 7 carbon atoms,

- R? is alkyl of 1 to 7 carbon atoms, R is alkyl of 1 to 7 carbon atoms,R and R each denotes the radical:

in which R and R have the above meanings or one of the radicals R and Rdenotes alkyl of 1 to 8 carbon atoms, and X is an oxygen atom or asulfur atom, which .ing the general formula:

X ll 0 1. a I R5 -(V) in which R R R R and X have the'above meanings, Rdenoteshydrogen or alkyl of 1 to 8 carbon atoms, one or "the radicals Rand R denotes hydrogen and the other denotes the radical -CH ORin-'which R [denotes hydrogen or alkyl of 1 to 8 carbon atoms withformaldehyde and an aldehyde having the formula Ha l- CHO s (II in whichR and R have the above meanings, in a molar ratio of about 121:3 in thepresence of a strong acid which does not oxidize under reactioncondition's' and at a temperature of from 0 to 120 C., the amount ofacid being from 1 to 30% by weight based on the total weight of thestarting materials. v 1

6. A process as in claim 3 wherein said process is carried out at atemperature of from 40 to C.

7. A process as in claim 4 wherein said process is carried out at atemperature of from 40 to 100 C.

8. A process as in claim 5 wherein said process is carried out at atemperature of from 40 to 100 C.

9. A process as in claim 3 wherein said process is carried out in thepresence of a solvent selected from the group consisting of water,tetrahydrofuran, and dioxane.

10. A process as in claim 4 wherein said process is carried-out-imthepresence-of asolvent selected from the group consisting of water,tetrahydrofuran, and dioxane.

'11.] A process as in claim 5.Wherein said process is carried out in thepresence of a-solvent selected from the groupconsisting; of water,tetrahydrofuran, and dioxane.

,3 ReferencesCited UNITED STATES PATENTS Blicke-Organic Reactionsvo1II-Wiley Press, 1942,

PrimaryExarninen R. V. RUSH, Assistant Examiner 'U.'S.Cl.X.R."

